Dear Tom and Ray:

My son and I were with our mechanic, Jeff, one Saturday morning when he was changing the oil in our minivan. Before he even touched the drain plug with a wrench, Jeff asked us where the oil had been changed last, because he saw red silicone around the drain plug. When he got the plug off, he saw why the silicone was there. The threads on the plug were stripped. The other garage had glued it in with the silicone instead of replacing it. I took the stripped plug back to the other shop, and they said they glue in stripped drain plugs all the time, and there's nothing wrong with it. Is gluing in a stripped drain plug with silicone a normally accepted automotive practice? Do you gentlemen do it in your shop? -- Ethan

TOM: No, it's not, and yes, we do.

RAY: Just kidding, Ethan. We never glue in drain plugs, and neither does any other reputable shop. Gluing in a drain plug is bogus. Or, as my brother likes to say, bo-o-gus!

TOM: Silicone is oil-resistant, but eventually it's going to break down and fail. And when it does, the drain plug is going to fall out. And if it happens to fall out while you're driving, it's goodbye, motor.

RAY: Sometimes drain plugs get stripped. And it might not have been the fault of that last shop (its oil change might simply have been the straw that broke the camel's back). But once it's discovered, it HAS to be fixed correctly. And if it's just the drain plug itself, you can replace it for a few bucks.

TOM: More often, though, the threads in the oil pan that the drain plug screws into are what get stripped. If it's the oil pan, there are still a number of pretty simple options: There are oversized plugs you can buy, rethreading kits with inserts or self-tapping plugs. And there are rubber expanding plugs that are almost foolproof -- i.e., we even let my brother install those.

RAY: But I wouldn't go back to those guys again, Ethan. They tried to cut corners on you, and they could have cost you a lot of grief and money. You're lucky that Jeff caught it in time.